The present invention refers to a high speed boat in which is used a pump driven by a driving motor constituted by for instance a petrol engine or a diesel engine. The pump pumps up water and generates a jet which can be directed and given different pressures, whereby such a boat can be propelled at a high velocity. Known boats has the driving motor directly coupled to the shaft of the pump and this has among other things the drawback that it becomes necessary to sometimes use a gear-box between the motor and the pump shaft. Further the shaft that drives the pump gives rise to certain flow problems.